Notices were shoved through the mail slots at the sprawling Springhill Lake Apartments in Prince George's County early last week saying that the thrice-yearly changing of furnace filters would occur on Wednesday.

Coworkers of James Brown, who had worked as a maintenance man at the rental development for 12 years, say they are confident that Brown followed the standard procedure as he made his rounds last Wednesday.

That means that before he used the passkey to enter the two-story town house of Anthony Zavosky at 9160 Springhill Lane at 3 in the afternoon, he would have knocked on the door. Getting no response, Brown would have entered, called out and then walked upstairs to the master bedroom and replaced the filter in the duct, located in a closet.

But before Brown--the used filter still in his hand--retraced his steps to the front door, he was dead, shot and killed as a burglar.

Zavosky, a District police officer who had worked the 11 p.m. to 7 a.m. shift, later told Greenbelt police he had been sleeping in the back bedroom when he heard what he thought was a burglar and, seeing someone going down the stairs, fired at him with his service revolver.

Brown, 53, and his wife, Doretha, had been employed at the Springhill development--she as a custodial worker, he as part of the maintenance crew--since moving north from Rocky Mount, N.C., in 1969. Traveling between their East Baltimore row house and Greenbelt, they made the 70-mile round trip together each day.

"I can't understand why they would do this," said Doretha Brown. "The undertaker said he was shot four times in the back."

Dr. Ann Dixon of the state medical examiner's office has ruled Brown's death a homicide, caused by multiple gunshot wounds, but she would not say if he was shot in the back.

Zavosky, 24, a four-year member of the Metropolitan Police Department, has been placed on administrative leave pending the outcome of an investigation into the shooting. He has been unavailable for comment.

Greenbelt police said they have turned over results of their investigation to the office of the Prince George's state's attorney.

Greenbelt police Lt. John Krob would not say if Zavosky or his roommate had received notice of the maintenance. He also declined to say whether Zavosky gave the customary police warning or if any words were exchanged before the shooting.

"No decision has been made because it has not been reviewed as yet," said Stephen Orenstein, in charge of the investigative section of that office. "If we believe there was a criminal act, then we will present it to a grand jury," Orenstein added, noting that the earliest it could reach a grand jury would be March 3.

Brown's wife of 33 years cannot understand what happened, nor why Zavosky "is still walking around. If it was my husband who shot him, you know where he would be. If he is a police officer, he is supposed to know when to shoot and when not to shoot," she said. "He is a cold-blooded killer."

According to a number of residents interviewed, Brown was known as a man who would go out of his way to do a favor. And many of his coworkers said they often turned to Brown for advice.

"I tell you he could be my old man--and he was colored and I'm white," said one worker. "He was like one of the old southern gentlemen you see on a porch waving at you as you go by," he added.

Trying to explain how well Brown was liked, he pointed to Zavosky's town house and said, "I'll tell you how well--that man had better leave."

Two doors away, Mary M. Miller was holding the printed note reading "CHANGED FILTER" with the initials "JB" that Brown left there about three hours before he was killed. He had left it in on her dresser in the midst of her jewelry.

"I never had to be here--that's how much I trusted that man," said Miller, who knew him better than most tenants because she is usually home and has lived there 10 years.

"He was one honest, nice man," said Miller. "I feel very bad."

Springhill property manager Romas R. Horton said his office has been flooded with calls from concerned tenants, several wishing to donate money to a fund for Brown, the father of five children and two foster children.

"Their response indicates the type of individual we lost," said Horton. "We all just can't believe we've lost a person as close as James Brown. We don't have any words to express our feelings."

Horton said he was helping Mrs. Brown make arrangements for the funeral, scheduled for tomorrow in Rocky Mount.

Doretha and James Brown met in 1946, when they both worked on adjoining tobacco farms near Rocky Mount. She said they would talk when the two groups of workers took water breaks from the back-breaking work. They were married two years later when she was 17.

James Brown had been working a variety of handyman and farm jobs there when a cousin told him about a job at Springhill Lake. The family then moved to Baltimore.

"At that time, we thought it would be a better change in life," said Mrs. Brown, who started working at the complex three months after her husband.

Doretha Brown is not sure she will ever return to the custodial department office, located less than 100 yards from where her husband was killed.

Coworker Arthur Pratt has similar feelings about working inside the apartments: "I don't even want to go in anymore--but it's my job." Pratt, a maintenance man for eight years, said, "I'm going to look both ways, and then scream, from now on."